1. Field of the Invention
The present invention relates to a danger alarm system of the type having a multiplicity of alarm circuits which are connected to an exchange by way of respective lines, and more particularly to such a system in which the state of the signals can be determined in the exchange via testing devices and indicated by an evaluation output device, wherein a write-read memory is provided in the exchange for storing the busy state of each line and a multiplex interrogation device is provided in order to interrogate the individual lines and the respective storage locations of the memory, and further wherein the interrogated alarm signals, together with the interrogated memory signals, are fed to a comparator and can only be transferred to the output device when the respective storage location is determined as busy.
2. Description of the Prior Art
In danger alarm systems, for example in public fire alarm systems, all components important for the function must be automatically monitored. A breakdown of one of the components must be indicated as a malfunction. Generally, such systems are modularly designed, in particular several lines can be connected to the connecting modules of the lines and of the input and output elements. It is therefore necessary to assign the correct display to the signals which are actually connected. and to take care that no malfunction indications are effected by the lines which are not connected.
In conventional systems this is done in two ways. The transmission of the alarm is arranged with the aid of specific lines, in the first case, and, if not desired, is prevented by interrupting these lines. In another case, a functioning operation is simulated, for example, by means of a particular terminal element which simulates an alarm ready for use. In both cases, an operation by hand must be undertaken in the wiring of the system with each alteration. The screwing or soldering operations necessary for this purpose require excessive time and present the problem, moreover, that there is always a danger of line switchings and improper connections.
In order to avoid the above disadvantages, it has been suggested to store all of the alarm configuration in a write-read memory in the exchange and to evaluate the alarm signals only when the respective alarm is indicated as being present in the memory. However, the writing of the memory by hand is cumbersome, at least for larger systems in particular, as the total signal configuration must be newly stored after every network breakdown or each time the system is switched off.